How to completely wipe an internal laptop HD

Zeroing a Hard Disk Drive

Warning! This procedure will destroy all data on your Hard Disk Drive. Be sure you have an up-to-date, tested backup of at least your Users folder and any third party applications you do not want to re-install before attempting this procedure.
Boot from the install CD holding down the "C" key.
Select language
Go to the Utilities menu (Tiger) Installer menu (Panther & earlier) and launch Disk Utility.
Select your HDD (manufacturer ID) in left side bar.
Select Erase tab
Select the a volume under Manufacturer ID (usually Macintosh HD).
Check to be sure your Volume Name and Volume Format are correct.
Select on Security Options button (Tiger) Options button (Panther & earlier).
Select Zero all data. (This process will map out bad blocks on your HDD. However, it could take several hours. Simply clicking the Erase button is quicker. It will do a simple erase, but will not be as secure.)
Click OK.
Click Erase button
Quit Disk Utility.

Please do not heistate to post back should you have further questions or comments.

Good luck.

cornelius

Message was edited by: cornelius

Mike:

So if I just click erase, it will still delete everything right?

Right.

Good luck.

cornelius

So if I just click erase, it will still delete everything right?

If you click erase it will remove the file directory but will not remove the file contents. It is easy to use a file recovery application and reconstruct files from an "erased" hard drive.

You need to select the "write zeros to drive" option to actually overwrite the data on your drive. Simply clicking on the "erase" button will not do this. The zero data option presents you with the choice of one complete overwrite (good) seven complete overwrites (seriously hashing the data on the drive) or thirty something overwrites (for the completely paranoid). At least choose the one time overwrite. Otherwise the data will still exist on the drive in recoverable form.

The OP was adivsed in my initial post about zeroing the HDD, and about the lack of security of a simple erase. His response was

I'm not concerned about the security, since I have nothing valuable on it anyway. (My old HD died last week, so this one is a brand new replacement.)

In other words, he may choose a simple erase in full awareness of the security risk.

Cheers.

cornelius

Mike:

I've read that zeroing a drive can damage it, similar to Defragmenting in Windows. Is that true?

To the best of my knowledge it is not true. During the zeroing process the computer writes zeros to each block of the volume thus over-writing any data that is on it in the same way it writes data. In the process of writing zeros, it spares out bad blocks. If your HDD is alreading failing it will not be able to restore it.

Good luck.

cornelius

Excuuuuse me.

I've read that zeroing a drive can damage it, similar
to Defragmenting in Windows. Is that true?

It better not be true, since I've been zeroing out the drives on my new computers as soon as I get them, and for a while now, too!

Actually, my theory is this: If the disk has a defect, it's possible that zeroing the drive could cause it to show up. That would be better when there's nothing else on the drive than to have it show up when I do a software update a year or two later, when the drive is full of files I'd rather not lose

And, as Cornelius points out, zeroing the drive maps out bad sectors. I used that technique to fix a PowerBook HD with bad blocks, and as far as I know, that PowerBook is still going strong two years after I did that. I don't have it any more, but the people I sold it to would probably have said something if it gave up the ghost.

charlie